Hobbled Hubble's Getting Wakeup Call From Discovery

CAPE CANAVERAL — Superlatives heaped on the Hubble Space Telescope often are as lofty as the observatory's perch in orbit 370 miles above Earth.

It's been called the most successful science mission in history, a window on the creation of the universe, and the crown jewel of the National Aeronautics and Space Administration's growing array of space-based telescopes.

But the accolades are not just Hubble hyperbole. After a rocky start, the telescope's discoveries have reshaped humankind's understanding of the cosmos. Exotic images of newborn galaxies, exploding stars and other celestial oddities have amazed scientists and the public alike, confirming some long-held theories and disproving others.

"Hubble has done a real good job of putting us in our place," said Ed Weiler, NASA's associate administrator for space science.

For now, however, new Hubble discoveries are on hold. The telescope went into a protective sleep mode on Nov. 13 when the fourth of six gyroscopes used to point the observatory at distant objects failed.

Seven astronauts will try to wake Hubble up during a high-stakes service call scheduled to lift off aboard shuttle Discovery between 9:18 and 9:59 tonight.

Discovery's veteran international crew is commanded by five-time shuttle flier Curt Brown. Four spacewalkers -- Steve Smith, Mike Foale, John Grunsfeld and Swiss astronaut Claude Nicollier -- will pair up for four repair trips outside the shuttle. French astronaut Jean-Francois Clervoy will use Discovery's robot arm to grab Hubble from orbit and move the spacewalkers around the telescope. Pilot Scott Kelly, the flight's lone rookie, will help Brown fly the shuttle.

The critical 10-day mission initially was scheduled for June 2000. But the third of Hubble's six gyroscopes failed last winter. That left only three working, the minimum needed to continue observations. To guard against losing another gyroscope, NASA managers split the 2000 mission in half, moving the first flight up to this October and scheduling the second part for mid-2001.

But repairs to damaged wiring throughout the shuttle fleet and other problems delayed Discovery's launch from October to December. In the meantime, a fourth gyroscope failed, transforming the delicate, pressure-packed maintenance flight into a rescue mission.

Hubble already was messed up in April 1990 when Discovery deposited the 43-foot telescope into orbit. The curvature of a mirror was slightly off, and nobody had caught the mistake. As a result, Hubble arrived in space with blurred vision.

Science's loss was David Letterman's gain. "Hubble Trouble" soon became a staple of the late-night comedy circuit. NASA was a laughingstock.

Astronauts on the first Hubble repair mission in December 1993 silenced hecklers and fixed the problem by installing corrective lenses. It was a landmark shuttle flight, transforming a public relations disaster into one of NASA's greatest post-Apollo triumphs. More importantly to scientists, Hubble was ready to start rewriting astronomy books.

A successful return visit by the shuttle in February 1997 outfitted Hubble with upgraded scientific instruments. Three more missions -- this month's and two others, scheduled for 2001 and 2003 -- are designed to keep Hubble working until 2010, five years beyond its originally planned 15-year lifetime. Afterward, it likely will be boosted to a higher orbit for safekeeping or brought home aboard the shuttle as a museum piece.

Hubble hasn't been cheap. The cost over the life of the program, including $1.6 billion for the telescope's original development, is estimated at about $5.7 billion. But astronomers say the price is a bargain.

"The quantum jump in resolution that we get with Hubble -- which is nearly a factor of 10 -- is something that has allowed us to look so much deeper into the universe than anything that has been used before," said Nicollier, who also was part of the crew on the first Hubble repair mission.

Scientists say Hubble has helped them better understand the universe in at least three key areas:

Snapshots of stellar nurseries have confirmed long-held theories about the birth of stars.

Deep-space studies of galaxies have enabled astrophysicists to more precisely estimate how fast the universe is expanding, as well as its age, fine-tuning theories by the telescope's namesake, astronomer Edwin Hubble.

Studies of areas near suspected black holes -- massive collapsed stars at the center of galaxies where gravity is so intense even light can't escape -- have virtually confirmed their existence.

Accomplishments such as those have led Grunsfeld and the mission's other astronomers, Foale and Nicollier, to discuss the 12-ton telescope with an almost religious reverence.

"This is without a doubt the Holy Grail for astronomers, to be able to go up and work on, but also climb inside of, the Hubble Space Telescope," Grunsfeld said. "It also puts a lot of pressure on [us]."

That pressure will get intense on Discovery's third day in orbit. After two days of catching up, Brown will rendezvous with Hubble and move the shuttle into position for Clervoy to capture the telescope with the 50-foot robot arm. With Hubble drifting in its sleep mode, the rendezvous will be slightly more tricky than originally planned. If all goes well, the last human spaceflight of the millennium will end with Discovery's landing at Kennedy Space Center on Dec. 26 at 6:56 p.m. If everything checks out, Hubble will be back in action early next year.